CBSE Questions for Class 11 Medical Biology Plant Kingdom Quiz 11 - MCQExams.com

• Agar, or agar-agar, is a jelly-like substance, obtained from red algae. Agar is a mixture of two components: the linear polysaccharide agarose, and a heterogeneous mixture of smaller molecules called agaropectin.
• Blue-green algae can be helpful in agriculture as they have the capability to fix atmospheric nitrogen to the soil. This nitrogen is helpful to the crops. Blue-green algae are used as a biofertilizer.

• Chlorophyll a and b are found in members of Chlorophyceae.
• Chlorophyll a,c and fucoxanthin are principal pigments found in Phaeophyceae.
• The members of Rhodophyceae are commonly called red algae because of the predominance of the red pigment r-phycoerythrin in their bodies. 
• Apart from this, other major pigments found in them are chlorophyll a and chlorophyll d.

• The sporophyte in mosses is more elaborate than that in liverworts. Liverworts develop a small sporophyte, whereas mosses develop a comparatively long and slender sporophyte with a better spore dispersal mechanism.
  
• Salvinia is a fern that is heterosporous, producing spores of differing sizes.
  
• In a diplontic life cycle, the dominant free-living phase is the diploid (2n). The sporophyte is photosynthetic. The gametophytic phase is represented by single to few-celled haploid gametophytes. All seed-bearing plants, i.e., gymnosperms and angiosperms exhibit this type of life cycle.
  
• The male and female cones are borne on the same tree in Pinus.
  

•  In Rhodophyceae, food is stored as floridean starch.
• Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous.
• The sporophyte is the dominant, photosynthetic, independent phase of the plant. The gametophytic phase is represented by the single to the few-celled haploid gametophyte. This kind of life cycle is termed as diplontic. 
• The gymnosperms (gymnos: naked, Sperma: seeds) are plants in which
  
• the ovules are not enclosed by any ovary wall and remain exposed, both
• before and after fertilization. Hence, II and III are correct, I and IV are wrong.
• So, the correct answer is "II and III are correct, I and IV are wrong'.
  

• Siphonogamy is a condition in plants in which pollen tubes are developed for the transfer of the male cells to the eggs
  
• Zooidogamy is a type of plant reproduction in which male gametes (antherozoids) swim in a path of water to the female gametes (archegonium)
• Cycas is the genus belonging to family Cycadaceae. Cycas is a very ancient genus of trees. It is noted that fertilization in cycas exhibit both siphonogamy (formation of pollen tube) and zoidiogamy (participation of ciliated male gametes). Hence In Cycas, fertilization occurs through. both siphongamy and zoidiogamy.
• So, the correct answer is 'Both B and C'.

A.Correct option -B
B.Explanation for correct option -B 

• Cycas is a living fossil as it has restricted occurrence in certain areas. Cycas is the type genus and the only genus recognised in the family Cycadaceae. 
• Cycads are seed plants with a long fossil history. They are gymnosperms (naked seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination.
  
• The genus is native to the old world, with the species concentrated around the equatorial regions of eastern and southeastern Asia. 

Correct Option: C

Explanation:

• Agar-agar is a gelling agent with unbranched polysaccharides and is used in microbiology as a solidifying agent of liquid culture mediums. It is extracted from the cell wall of red algae, mostly from Gelidium species and Gracilaria species.
• Laminaria and Sargassum are the brown algae and are cultivated as a crop. 
• Algae are green photosynthetic organisms that release oxygen in immediate vicinity through the process of photosynthesis. 
• The cell wall of brown algae has an inner cellulose layer and outer gelatinous coat which is composed mainly of algin, it is used as an emulsifying agent and a stabilizer.